About Ticks
Ticks have existed for 90 million years, with more than 800 known species throughout the world. Of these, 200 can be found in the United States. Often thought to be insects, these pests are actually part of the spider family.
Closely related to spiders, ticks also belong to the arachnid group. Relying on the blood of their hosts, ticks are likely to move from one mammal to another in order to survive. Due to their transient behavior, these pests are vectors of a number of diseases, including Rocky Mountain Spotted Fever and Lyme disease.
Ticks are parasites that feed on the blood of humans and animals. They are common foes of house pets and people who spend time outdoors.
What do ticks look like?
Ticks range in size from nearly visible to 1/4” and their bodies are flat before feeding. They are reddish-brown, orange-brown, brown, or black in color. Some ticks will turn a greyish-white when their bodies become engorged, or rounded, after a meal.
The body of a tick consists of a head, thorax, abdomen, and four pairs of legs. They also have three important mouthparts — chelicerae, hypostome, and palps — used to pierce the skin and draw blood from the host. Ticks are divided into two groups: hard and soft. Hard ticks have a hard plate, called a scutum, on their backs. Soft ticks do not have a scutum but do possess leather-like skin.
The hard ticks’ development cycle takes them from egg to larvae to nymph to adult in what is often called a three-host cycle. Ticks die shortly after mating and laying eggs on the ground. The eggs hatch into larvae. At the larval stage, ticks attach to the first host, and once they have had a sufficient blood meal, they detach and return to the ground where they develop into nymphs. The nymph — which is sometimes called a seed tick — attaches to a second host, once again feeding. When sated, the nymph leaves the host, returning to the ground to finish its evolution into an adult tick. Both males and females attach to a third host and mate, beginning the cycle once again.
The lifecycle of soft ticks varies, as they remain in the nest of their host and may feed on the same animal or group of animals during their development.
Life Cycle
Most ticks develop through four stages: egg, larva, nymph, and adult. Each active stage requires a blood meal from a host before the tick can molt and progress to the next stage. The full life cycle typically takes one to three years depending on the species and environmental conditions.
Larvae hatch with six legs and are extremely small. After feeding, they molt into eight-legged nymphs. Nymphs feed once more before molting into adults. Adult females feed, mate, and then drop off the host to lay thousands of eggs in the environment before dying. Ticks do not jump or fly. They climb vegetation and wait with front legs extended for a host to brush past, a behavior called questing.
Health Risks
Ticks are vectors for more than a dozen disease-causing agents in the United States, including bacteria, viruses, and parasites. The most significant include:
- Lyme disease: The most commonly reported tick-borne illness in the US, with an estimated 476,000 cases annually. Symptoms include fever, fatigue, joint pain, and in many cases a bullseye-shaped rash at the bite site. Transmitted by black-legged ticks.
- Rocky Mountain spotted fever: A bacterial infection that can be life-threatening if not treated promptly. Symptoms include fever, headache, and a spotted rash. Transmitted by American dog ticks, brown dog ticks, and lone star ticks.
- Ehrlichiosis and anaplasmosis: Bacterial illnesses causing flu-like symptoms including fever, chills, muscle aches, and headache. Transmitted by lone star and black-legged ticks.
- Alpha-gal syndrome: An allergic reaction to red meat triggered by lone star tick bites. Symptoms can range from hives to anaphylaxis and may develop hours after eating beef, pork, or lamb.
- Powassan virus: A rare but serious virus transmitted by black-legged ticks that can cause encephalitis. Unlike Lyme disease, Powassan virus can be transmitted in as little as 15 minutes of attachment.
Disease transmission risk increases with the length of time a tick remains attached. Most bacterial tick-borne diseases require the tick to feed for 24 to 48 hours before transmission occurs, which is why prompt tick removal matters.
Frequently Asked Questions
Can ticks live in my home?
Most tick species cannot survive long-term indoors because they require outdoor humidity levels to survive. The brown dog tick is the exception and can complete its entire life cycle inside a home or kennel.
Do all ticks carry Lyme disease?
No. Only black-legged ticks (deer ticks) and western black-legged ticks transmit Lyme disease. Other species transmit different diseases. Not every individual tick of these species is infected, but the risk cannot be determined by looking at the tick.
How do I safely remove a tick?
Use fine-tipped tweezers to grasp the tick as close to the skin as possible and pull upward with steady, even pressure. Do not twist or jerk. Do not use heat, petroleum jelly, or other folk remedies, as these can cause the tick to release more fluid into the bite. After removal, clean the area with rubbing alcohol or soap and water.
How long does a tick need to be attached to transmit disease?
For most bacterial diseases like Lyme, the tick generally needs to be attached for 24 to 48 hours. Powassan virus is an exception and can transmit in as little as 15 minutes. This is why checking for ticks promptly after outdoor activity is important.